The fortuitous combination of atmospheric gases that may life as we know it possible may have a decidedly extraterrestrial origin, stemming not from the actions of terrestrial volcanoes but from the appearance of comets.

Scientists have long been puzzled by the mixture of gases in the Earth’s atmosphere ”“ and by the origins of those gases. For years one of the most popular theories has been that the gases in the Earth’s atmosphere are the result of the eruption of volcanoes. As those gases bubbled up from those ancient volcanoes, the theory goes, they helped to create the atmosphere as we know it today.

But recently researchers at the University of Manchester in the UK came up with a different theory for the origins of the Earthly atmosphere, based on their findings after they collected samples of krypton gas hundreds of meters below New Mexico.

Researcher Greg Holland and his colleagues at the University of Manchester found that the area they studied was rich in heavier isotopes of krypton but poorer in lighter versions of the gas. In fact the composition of the samples closely resembled that found in meteorites, lending further credence to an exterritorial origin of the terrestrial atmosphere.

The comet theory supposes that the current atmosphere of the Earth has its origins not in volcanoes that spewed krypton and other gases into the air but in the bombardment of the earth by thousands icy comets. Specifically this emerging research is focused on the Kupier Belt, which formed when the solar system was born. The millions of icy bodies in the Kupier belt have been found to contain a noble gas signature very similar to that of the Earth’s present atmosphere.

Scientists already know that a shift in the orbit of gas giant Jupiter took place some 4.5 billion years ago, and that shift may have been enough to move the Kupier belt and release those comets on a collision course with Earth. It is an interesting theory, and one that is bound to gain additional attention as new evidence is discovered.

The New Frontiers program came about following a study in 2001 which was conducted to look at the state of solar system exploration at that time and identify priorities for continued exploration during the 10 year period 2003 to 2013. The study identified five medium class missions that were considered of importance and the New Frontiers program was set up to examine and implement these.

The first mission launched was named New Horizons and its goal is to visit and explore Pluto. It will also visit one or more Kuiper Belt objects during the mission. New Horizons was launched in January 2006 and is scheduled to reach its destination by July 2015. The second New Frontiers mission is named Juno and has been designed to conduct an in-depth study of Jupiter. It is currently scheduled for launch in August 2011. At the end of December 2009 NASA announced that three candidates had been chosen for the third New Frontiers program and these include some exciting possibilities for solar system exploration.

The first potential candidate is named the Sunrise and Atmosphere Geochemical Explorer (SAGE) and would comprise a mission to Venus. On arrival it would release a probe into the atmosphere of the planet which would undertake extensive measurements as it descended to the surface of Venus. Upon landing the probe would conduct studies to assess the composition and mineralogy of the surface material.

The second candidate is called the Origins Spectral Interpretation Resource Identification Security Regolith Explorer or Osiris-Rex for short. This mission would be designed to travel to and orbit an asteroid. Extensive measurements of the asteroid would be taken while the spacecraft was in orbit around it. Samples would then be collected from the surface of the asteroid and these would be returned to Earth. These samples would be used to assist in the study of the formation of the solar system and the origins of the molecules necessary for life.

The third candidate would send a spacecraft to land in an area near the south pole of the moon which would collect lunar material and return it to Earth. This mission is known as Moonrise: Lunar South Pole – Aitken Basin Sample Return Mission. The returned lunar sample would be used to help gain an insight into the early history of the Earth-moon system.

Each of the candidates will now have around a year to complete a detailed concept study which is required to consider the feasibility of implementation, the costs involved and technical plans for carrying out and completing the mission. The teams will receive approximately $3.3 million to undertake the concept study and it is currently proposed that selection of the winning candidate will be made in mid 2011. Planning and preparation for the chosen mission would then take around seven years and the spacecraft has to be ready for launch by no later than the end of December 2018.

Each of the missions represents an opportunity for further study of a celestial body and the winning candidate is sure to advance our knowledge of the solar system. All three are potentially exciting opportunities to learn something new and any one of them would provide scientists with a rich source of data. Only time will tell which of the candidates will be successful and for now the three teams have a year of hard work ahead of them.

The Jupiter flyby was a huge success, allowing observations of the giant planet and its moons in unprecedented detail.  Among other things, information was gathered about the atmosphere and weather of Jupiter.  Data on cloud composition was collected by the visible light, infrared and ultraviolet remote sensing devices, and ammonia was observed welling up from the lower atmosphere to form clouds.  Lightning strikes were observed at the poles, the first polar lightning ever seen off Earth, and from this it was learned that heat moves evenly through water clouds at all latitudes across Jupiter.  New Horizons also made size and speed measurements of waves in the Jovian atmosphere, indicating strong storm activity beneath, and obtained close-up images of the Little Red Spot, a smaller version of the Great Red Spot.  The smaller feature is about half the size of the bigger one, or about 70 per cent of Earth’s diameter.

New Horizons obtained the clearest images yet of the tenuous Jovian rings.  Here clumps of material were observed that may be from a recent impact within the ring system.  The probe got a detailed view of the ring dynamics involved here, with moons Metis and Adrastea shepherding the materials around the rings.  A search for small moons within the rings yielded negative results.

The probe performed observations of Jupiter’s four largest moons, focusing especially on Io, closest to Jupiter and volcanically active.  Eleven volcanic plumes of varying size were seen, three for the first time.  One of these, a 200-mile-high eruption from the volcano Tvashtar, offered a chance to see the structure and motion of the plume as it condensed and fell back to the surface.  Instruments picked up infrared radiation from at least 36 volcanoes on Io with lava temperatures about 1900 degrees Fahrenheit, which is comparable to volcanoes on Earth.  Io is the most active body in the solar system, and more than 20 geological changes had occurred since the Galileo Jupiter orbiter was there in 2001.  Observations of Io while in Jupiter’s shadow showed glowing clouds over many of the volcanoes, a possible source of gas for Io’s atmosphere.

The probe passed down Jupiter’s magnetotail and got the closest-ever look at this region.  Particle detectors indicated that volcanic material from Io moves down the tail in slow-moving blobs.  Scientists are hoping to learn how these gases are ionized, trapped and energized by Jupiter’s magnetic field, and then finally ejected from the system.

New Horizons left Cape Canaveral in January, 2006.  It is the fastest spacecraft ever built, reaching Jupiter in only 13 months.  It is now about halfway between the orbits of Jupiter and Saturn, more than 743 million miles from Earth, and it will fly past Pluto and its moons Charon, Nix and Hydra in July 2015 before going deeper into the Kuiper Belt.

At present, the mission continues to go well.  In November of 2009, the probe was brought out of hibernation to repoint the communications dish antenna in order to keep up with the changing position of Earth around the sun.  This wake-up also provided an opportunity to download several months of stored data, correct a minor bug in the fault protection system software, perform adjustments to refine the craft’s trajectory, and upload instructions for the running of the craft from now until its next scheduled wake up in January 2010.

While New Horizons will not reach its destination until 2015, it will be able to perform some observations of Pluto and its largest moon, Charon, about a year earlier.  It will be taking pictures of the two at that point, and a few months later, it will be able to generate a map of Pluto.

The long approach will give an opportunity to watch seasonal changes in Pluto’s atmosphere.    Since 1989, Pluto has been heading away from the sun.  In 1999, it crossed the orbit of Neptune, once again becoming the outermost of the nine traditional planets.  It is now heading into its 200-year winter, when its atmosphere is expected to freeze and fall to the surface as snow, and because of this, the New Horizons mission will be the last chance to study the atmosphere of Pluto.  The probe will obtain information about its chemical composition, and also allow observations of cloud formation.  Clouds, probably composed of nitrogen or carbon monoxide, have already been observed in the thin atmosphere of Pluto.

Once New Horizons has passed Pluto, it will head out into the Kuiper Belt to find and study some of the mysterious bodies that exist there, which are thought to be icy and comet-like.  The probe will conduct a search for Kuiper Belt bodies, and when it finds them, will modify its own course to approach and observe them.  It is hoped that New Horizons will find six to ten of these bodies to study.

The outermost region of the solar system is a vast, dark area that is only beginning to reveal its secrets.   What else is out there?  Over the next few years, we will begin to find out.